Side entry flow spool and use thereof

ABSTRACT

The invention provides a side entry flow spool for use in production of oil and gas from a well. The side entry flow spool provides for a shift in the direction of flow of the hydrocarbons, from horizontal to vertical.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/719,719, filed Oct. 29, 2012, which is incorporated herein byreference.

FIELD OF THE INVENTION

This invention relates to a side entry flow spool and a method of usingthe side entry flow spool to export hydrocarbons from a horizontal flowline. The side entry flow spool is preferably integrated with a subsealanding string.

BACKGROUND

Safety and environmental concerns related to subsea production of oiland gas have heightened greatly, and there is renewed interest indeveloping systems that can be used to respond to the loss ofcontainment of the oil and gas at a subsea wellhead. The environmentaldamage that can be caused by loss of containment of oil and gas at asubsea wellhead is enormous and steps are being taken to address bothpreventing such a loss of containment and regaining control andcontainment in the event that oil and gas does leak to the environment.

To fulfill the requirement to transport hydrocarbons from a seabedinstallation to a production/storage/testing facility at the surface itis necessary to develop an enabling interface between the seabed systemand the surface system. The requirement for this item is driven by aneed to function effectively in all water depths from ultra deep, about3000 m, to shallow, about 100 m.

SUMMARY OF THE INVENTION

The invention provides a side entry flow spool comprising a forging withflanges located at the top and bottom; an inlet located on the side; anoutlet located at the top; and an internal cavity that is fluidlyconnected to the inlet and outlet wherein there is no opening at thebottom.

The side entry flow spool may be integrated with a subsea landing stringvia a latch to enable contained flow of well fluids from a damagedoffshore well to a vertical marine riser connected to a capture vessellocated at an offset distance from the incident well.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side entry flow spool connected to an anchor point and ablowout preventer.

FIG. 2 shows a more detailed view of a side entry flow spool.

DETAILED DESCRIPTION

The invention provides a system for transporting hydrocarbons from asubsea location to the surface of the water. The main feature of theinvention is the side entry flow spool and its use in conjunction withstandard equipment that is readily available and can be rapidly deployedanywhere in the world. The system may be used to transport leakinghydrocarbons that are captured by any subsea capture apparatus known toone of skill in the art. The system provides for the transport of thehydrocarbons from the leaking well a safe distance away and then to astandard floating vessel that does not require any custom modifications.This allows a leaking well to be contained using industry standardequipment in almost all aspects. The system may also be used totransport produced hydrocarbons from a production well.

The side entry flow spool may be used equally well in deep water or inshallow water, although the other equipment used would be different. Forexample, in deepwater, the side entry flow spool would be connectedthrough a riser to a floating vessel. In shallow water, the flow spoolcould be connected to a freestanding production riser that transportsthe hydrocarbon to a jack-up vessel. Further the need for BOPs and thelocation of BOPs could be different depending on the water depth.

The side entry flow spool is designed to allow connection between anysubsea architecture to any riser system which connects with a surfacevessel, mobile oil drilling unit, jack-up, work barge or other system.The side entry flow spool if structurally capable of working in thewater depth in the range of from less than 100 m to about 3000 m ordeeper.

The side entry flow spool is a bespoke piece of equipment designed toallow the conduit of wellbore fluids to pass from the subseaarchitecture to a vertical riser located at an offset distance from thewell which transports the product to a MODU or well intervention vessel.The side entry flow spool has the ability to marry these systems betweenthe extremes of ultra deepwater with a drillship/BOP and marine riser toshallower scenarios which only require a jack-up and free standingproduction riser.

The invention will be further described with reference to theillustrative embodiments shown in the drawings. The invention however isnot limited to the embodiments depicted in the figures.

FIGS. 1 and 2 depict a side entry flow spool 100 and the manner in whichit is connected to the system. The side entry flow spool has an inlet106 and an outlet 108. The inlet 106 is located on the side of the spooland provides a horizontal inlet into the spool. The outlet 108 islocated on the top of the spool and provides a vertical outlet from thespool. The configuration of the inlet and outlet provide a means forconverting horizontal flow into vertical flow that can be directedtowards the surface of the water. The side entry flow spool does nothave an opening in the bottom of the flow spool.

The inlet 106 may extend in the horizontal direction for connection withflow lines and/or jumpers carrying hydrocarbons. The inlet may beconnected to the flow lines and/or jumpers with any type of connectionknown to one of skill in the art. The connection may be flanged orotherwise, but it is preferred to use a connection that is easilyinstalled due to the desire to rapidly deploy this system.

The inlet of the side entry flow spool may be flush with the spool or itmay comprise a horizontal tubular that is connected to an opening on theside of the spool. Alternatively the horizontally extending tubular maybe integral with the body of the side entry flow spool. The inlet mayalso comprise one or more isolation valves. A double valve arrangementprovides industry standard isolation. The inlet is preferablyperpendicular to the outlet such that the horizontal flow is convertedinto vertical flow in the side entry flow spool. Other embodiments mayinclude an angled inlet at an angle other than ninety degrees to theoutlet.

The side entry flow spool may comprise one or more additional inlets 107that can be used for example, for chemical injection and/or flushing ofthe spool to remove solids that may accumulate at the point where thehydrocarbon changes direction from horizontal to vertical. The inletsmay also be used for pressure monitoring or for connecting to anotherside entry flow spool for daisy-chain production. The inlets may belocated on opposite sides of the side entry flow spool or they may belocated at other points along the side of the spool.

The side entry flow spool is preferably machined from a single piece ofmetal. The flow spool must be able to withstand the forces that areexerted on it from within by the passage of the hydrocarbon andexternally by the connections to other systems. The side entry flowspool may be coated with a protective coating to prevent corrosionand/or erosion to the internals of the flow spool. The corrosion may becaused by exposure to carbon dioxide, hydrogen sulfide and/or othercomponents of the hydrocarbons passing through the spool. The flow spoolis designed to withstand all types of conditions so that it can be usedin different applications without modification.

The side entry flow spool preferably has API flanges on the top 114 andon the bottom 112 to provide for connection to other subsea productionequipment. The side entry flow spool needs to be anchored to theseafloor and it is typically connected to a riser or BOP to carry thehydrocarbons to the surface of the water.

In one embodiment, a drill string 102 is inserted at least partiallybelow the seafloor 116 so it can be used as an anchor point for the sideentry flow spool. The drill string does not provide for the productionof hydrocarbons, but is only inserted deep enough to anchor the flowspool.

In another embodiment, the flow spool may be connected to a new orexisting well head. Further, in another embodiment where the flow spoolis used in shallow water, the side entry flow spool may be anchored by amud mat.

The side entry flow spool is preferably connected to a standard wellheadconnector 110 that is located on the drill string, wellhead or mud mat.The standard wellhead connector has API flanges and is connected to theside entry flow spool using these flanges. Alternatively, the flow spoolcould have a wellhead connector on the bottom that would connect to thewellhead.

The anchor point provides sufficient force to keep the side entry flowspool anchored in place regardless of the forces exerted on it by thesystems connected to the inlet(s) or outlets of the flow spool.

The side entry flow spool does not have an outlet in the direction ofthe seafloor, so the hydrocarbon is routed in a vertically upwardsdirection. In one embodiment, the outlet of the side entry flow spool isconnected to a blowout preventer 104. In another embodiment, the outletof the side entry flow spool is connected directly to a riser. The sideentry flow spool may be connected to a wellhead connector via the topflanges of the side entry flow spool. The blowout preventer would thenbe connected to the wellhead connector.

Further, the position of the blowout preventer allows the system to bepressure tested before use to ensure containment of the hydrocarbons.The blowout preventer may be any suitable type of blowout preventer orthe system may comprise more than one blowout preventer forming ablowout preventer stack.

The blowout preventer is connected to a riser that extends upwardtowards the surface of the water. The riser may be a top-tensionedriser. A production or test string may be located inside the riser toallow for the passage of hydrocarbons through the string upwards to thevessel or platform on the surface of the water.

The side entry flow spool may be designed to allow a subsea test tree oroilfield tubular string to be connected to the flow spool, with apressure seal. This is preferably accomplished by the use of a latch onthe bottom of the string that latches into the side entry flow spool.The flow spool can be machined or otherwise designed to allow the latchto securely connect to the side entry flow spool. The latch would belocated within the outlet of the side entry flow spool and preferablyconnected to the internal inner diameter section of the outlet of theflow spool. Crossover connections can interface with this latch bysimple compatible thread form.

In one embodiment, the side entry flow spool is used in combination witha subsea apparatus that is used to capture hydrocarbons that are leakinginto the water. Flow lines or pipelines may be installed that extendfrom the source of the leak to the side entry flow spool which may belocated a safe distance away from the leak, for example 500 to 2000meters.

In one embodiment, a drill ship through a drilling riser, drills a shortdistance into the seabed and inserts one or more pieces of drill stringat last partially below the mud line. The drill string acts as an anchorpoint for the system. A side entry flow spool is connected to the drillstring. The side entry flow spool is connected to the flow linescarrying hydrocarbon. The side entry flow spool has one or more inletson the side and one outlet on the top of the spool. The outlet isconnected to the floating vessel on the surface of the water. Theconnection is preferably via a production string or well test stringthat is run through the drilling riser. A blowout preventer ispreferably located between the side entry flow spool and the drillingriser.

In this embodiment, the drill string, drilling riser, drill ship andblowout preventer are industry standard equipment used to drill subseaoil and gas wells. Suitable drill ships are available throughout theworld and this availability provides one of the advantages of thisinvention. These ships can respond quickly to a leaking wellheadanywhere in the world without requiring the transportation of any largecustom equipment. Additional advantages are that the majority of theequipment needed for this operation is known and used for similarpurposes in deepwater exploration and production. The use of thisequipment does not require additional training and testing before use inthis application.

The drill ship may have facilities to separate and treat the oil and gasthat is being produced from the leaking well. In the alternative,another floating vessel may be moored near the drill ship and thehydrocarbons passing up through the drilling riser may be exported tothis other floating vessel for storage, separation or disposal. Forexample, the gas being produced from the leaking wellhead may betemporarily flared during the time period required to control the well.The other floating vessel may be a shuttle vessel that storeshydrocarbons and then transports them to a larger facility and thenreturns to receive additional hydrocarbons.

The drilling riser may be a top tensioned riser. A top-tensioned riseris a completely vertical riser system that extends vertically until justbelow the floating vessel. The floating vessel will move with the motionof the waves which could result in damage to the riser or subsea blowoutpreventer and side entry flow spool. A top tensioned riser is a rigidriser that is fixed to the seafloor and tensioned at the top. The toptension can be provided by buoyancy devices that are connected to thetop of the riser. The fluid flowing through the riser may pass from thetop of the riser through flexible lines to the floating vessel. In thismanner the movement of the floating vessel does not directly affect theriser or put stress on the riser.

The system may be used to capture hydrocarbons from a subsea apparatusplaced on a leaking wellhead. In another embodiment of the invention,the side entry flow spool may be used to export hydrocarbons from aregular producing well and provide the connection between a horizontalflowline and a vertical riser.

The invention also provides a method of capturing hydrocarbons from theleaking wellhead as further described herein. The method comprises firstinstalling a capping stack on top of a damaged subsea wellhead. Flowlines are installed along the mud line and are connected to the cappingstack. These flow lines may be connected to a flow line end terminationfacility, manifolds or other standard subsea oil and gas productionequipment. The oil recovery system comprising the blowout preventer,riser, side entry flow spool and anchor point are installed somedistance away from the leaking wellhead. Everything is connected andhydrocarbons can begin flowing to the floating vessel while the well isbrought back under control.

1. A side entry flow spool comprising a forging with flanges located atthe top and bottom; an inlet located on the side; an outlet located atthe top; and an internal cavity that is fluidly connected to the inletand outlet wherein there is no opening at the bottom.
 2. The side entryflow spool of claim 1 further comprising a machined internal profile forconnection with a latch mechanism located inside the forging that issuitable for connection with a subsea test tree or oilfield tubularstring.
 3. The side entry flow spool of claim 1 further comprising oneor more additional inlets located on the side of the forging.
 4. Theside entry flow spool of claim 3 wherein the one or more additionalinlets are suitable for one or more of the following: injectingtreatment fluids, connecting with another side entry flow spool,monitoring pressure or flushing the system.
 5. The side entry flow spoolof claim 1 wherein the inlet is a tubular that is integral to the sideentry flow spool.
 6. The side entry flow spool of claim 1 wherein theflanges are API standard flanges that can be connected with standard oiland gas industry equipment.
 7. The side entry flow spool of claim 1wherein the bottom of the side entry flow spool is suitable forconnection to a wellhead connector.
 8. The side entry flow spool ofclaim 1 wherein the top of the side entry flow spool is suitable forconnection to a blowout preventer or directly to a production string. 9.The side entry flow spool of claim 1 wherein the top of the side entryflow spool is suitable for connection to a wellhead connector so thatother standard oil and gas production equipment can be connected to thewellhead connector on top of the side entry flow spool.